Based on the configuration of the material handling system, items (e.g., cartons, cases, etc.) may travel through the material handling system in an unregulated fashion (e.g., clustered, overlapping, and/or non-single file flow) at an initial time. However, to aid in sorting items, for example into different divert lanes for shipment via a sortation conveyor, it is often advantageous to align the flow of items into a single file stream. A singulator (or singulator conveyor) is an example of a conveyor that accepts an unregulated flow of items and discharges the items as a single file stream. Singulators are often wide bulk conveyors accepting inputs at various points (for example from one or more collector conveyor) and aligning the input items such that the items are discharged as a single file stream. Singulators often include recirculation lines that convey items that have not been successfully placed into the single file stream (i.e., not singulated) back to the start of the singulator. Singulators often discharge the single file stream of items to a sortation conveyor.
Sortation conveyors have the ability to convey unit loads and selectively divert individual loads being conveyed off at desired destinations alongside the conveyor. Sortation conveyors are commonly used in unit handling for conveying mixed batches of loads and sorting them to planned destinations located along the length of the conveyor. There are several different types of sortation conveyors used for unit load handling applications, such as pop-up skewed wheel sorters, pivot wheel sorters, cross belt/tilt tray sorter, and sliding shoe sorter.
Sliding shoe sorters are very effective at high speeds in that the number and operation of the divert shoes may be configured to gently guide the load to a particular divert lane. Sliding shoe sorters have a carrying surface is made up of conveyor flights (slats or tubes), each of which are attached to a drive chain running just inside each sorter side channel. Sliding divert shoes, which are supported by the conveyor slats, push a load off the flight conveyor at an appropriate sort destination. The number of shoes used to divert a load is determined at induction, depending upon a length of the load. Rates up to 400 cartons per minute can be achieved thereby in part by sorting on minimum gaps between cartons.